In general, a method that is widely used for electroplating non-conductive plastic moldings to form a decorative film comprises, in succession, degreasing, etching, optionally neutralizing and pre-dipping, then applying a catalyst for electroless copper plating by using a colloidal solution containing a palladium compound and a tin compound, and optionally activating (performing accelerator treatment), followed by conductive film formation (electroless copper plating) and electroplating.
In such a method for electroplating non-conductive plastic moldings, an alkaline aqueous solution has heretofore been used as an electroless copper plating bath to form a conductive film. However, when an alkaline electroless copper plating bath is used to form a conductive film, a target non-conductive plastic easily undergoes hydrolysis; thus, when a film is formed by electroplating on the formed conductive film, sufficient adhesiveness cannot be obtained (Patent Literature (PTL) 1).